Abstract

Ingestion of carbohydrate during exercise is common in order to provide an exogenous substrate for oxidation and to improve performance. The rate at which a solution is emptied from the stomach is an important step in this process. Acute changes in blood glucose concentration significantly influence gastric emptying rate (GER). Animal studies have suggested that exposing the intestine to glucose and artificial sweeteners leads to an increase in mRNA transcription and the number of SGLT-1 transporters within the intestine. This may influence the rate of glucose absorption and GER. The aim of this study was to investigate the effects of pre-exercise sucralose ingestion on GER during exercise. Nine healthy males volunteered to participate in this study, which involved completion of two experimental trials undertaken in a fasted state. Over a two hour period, participants ingested 400 mL of water (C) or 400 mL of water containing 159 mg sucralose (S) in equal aliquots every 15 minutes. Following this, 600 mL of a commercially available carbohydrate-electrolyte solution containing 100 mg ¹³C sodium acetate was ingested prior to undertaking 90 minutes of cycle exercise at 70% of heart rate reserve. Breath samples were collected pre- ingestion and at 15 minute intervals throughout exercise for measurement of GER. No differences (P>0.05) were observed between trials in heart rate or rating of perceived exertion during exercise. Half emptying time of the solution was 47±16 (C) and 44±15 (S) minutes (P=0.555) while time of maximum rate of gastric emptying was 39±10 (C) and 34±10 (S) minutes (P=0.160). No difference (P>0.05) between the trials was observed in delta over baseline breath values. The results of this study indicate that pre-exercise sucralose ingestion does not influence GER during exercise. This may be due to the time period of sucralose ingestion not being sufficient for adaptation to occur.